the modeling investigation in this paper discusses the system level effects of a toxicant on a three species food chain system. in the models, we have assumed that the presence of top predator reduces the predatory ability of the intermediate predator. the stability analysis of the models is carried out and the sufficient conditions for the existence and extinction of the populations under the ...

web 2.0 is not a single technology or standard but rather a set of concepts and features. web 2.0 concepts and features call for further attention. since, previous studies have only addressed only some of these concepts and features. in order to give a comprehensive view of web 2.0, these features are collected through literature review and a framework of web 2.0 features is presented. also, du...

the morphological river evolution at long-time (centuries and even millennia) and large spatial scale (watersheds of several square kilometres) can be described by means of simplified 1d models, able to simulate the variation of bed elevation and grain size composition at non-detailed scales, involving a reduced computational effort. the erosion and deposition phenomena acting along rivers can ...

introduction: many organizations, especially service oriented ones, relative to their goals and mission, have a special view towards quality phenomena and its management. methods: this paper analyzes medical service quality in one case the internal section of shaheed rahnemoon hospital based on the basis of gap analysis model and servqual technique. a questionnaire was designed and applied to m...

Nowadays, numerous processes of any supply chain are done by suppliers and consequently they cause a massive amount of pollution released to the nature. Hence, greening the suppliers has become a necessity. Although most of green supplier development programs need high investment, formal optimization models that address this issue are very rare. This paper mainly aims to address this prob...